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VIBRATOR TYPE C ENTR IFUGAL SWITCH Filed Nov. ll, 1924 :NvEN pRs OTTO BOHM B WIL LM MUSER TT EY Patented Jan. 27, 1931 UNITED STATES PATENT orricr.

OTTO B6HM AND WILHELM MOSER, OI BERLIN, GERMANY, 'ASSIGNOBS TO GESELL- SCHAFT FtlR DRAHILOSE TELEGRAPHIE M. B. 11., 0F BERLIN, GERMANY, A GOR- I'ORATION 0F GERMANY VIBRATOB-TYPE CENTRIFUGAL SWITCH Application filed November 11, 1924, Serial No. 749,202, and in Germany November 26, 1928.

Our invention relates to means for governing the speed of machines and more particularly, electric motors byemploying a centrifugal device which controls the current to some part of the machine.

It has for its object to provide such means using a vibrating contact cooperating with a fixed contact, the vibrations being caused by the action of gravity when the governor revolves and the relative periods of opening and closing of the contacts controlling the amount of current thru them and being controlled.

by the speed of rotation.

A further object of the invention is to so arrange the vibrating contact that it is not directly affected by centrifugal force, but is controlled thru an amplifying arrangement only by the vibration of a mass which is affected by centrifugal force,

A further object of the invention is to have the vibrating contact tuned to the desired speed of rotation to increase the amplitude of its swing.

Other objects will be apparent from the following description and appended claims when considered with the accompanying drawing in which the single figure represents schematically our invention.

There are speed regulators for-electric motors which work according to the principle of the centrifugal regulator.

In our invention We provide a mass (called centrifugal mass in the following) compulsively rotating together with a rotating element of the machine it is desired to govern and which is under the influence of the centrifugal force and of a spring force. This mass effects a contact for the critical speed and thus through suitable electric connections and apparatus, the in ut of the motor is regulated. The centri ugal mass of such a centrifugal regulator may be also always under the influence of the force of gravity. If the plane of rotation is not horizontal, the force of gravity causes the centrifugal mass to oscillate, so that, in case of the critical speed, the contact is periodically opened and closed in the measure of the time of rotation.

It has been found that these oscillations of the contact are not only harmless but even advantageous in so far as they smooth out the process of regulation. The regulation proceeds in such a way that the ratio of the'contact time and of the breaking time for every revolution decreases, or increases, whereby the current flowing across the contact to the motor is decreased or increased respectively in a regulating sense.

By this means a vibratory regulator action is obtained which produces an effect upon the driving motor somewhat similar to the well known Tyrell regulator.

A disadvantage of the previously known arrangement is, that the amplitudes of the oscillating contact are small and the higher the speed, the smaller they are. For high speed electric motors the movement of the contact easily becomes so small that it is not possible to increase the regulating currents and voltages to the necessary amount.

This disadvantage is eliminated by the present invention according to which a movable arm or lever, the end of which carries the movable contact and which is submitted to as little centrifugal force as possible, is connected to the centrifugal mass. The an rangement is such that the arm or lever, and

accordingly the movable contact has a swim of greater amplitude than the centrifuga mass. The movements of the contact thus already increased are still more increased if the arm or lever is elastic and tuned to resonance with the critical speed.

Referring to the drawing, a is a circular disc through the centre of which the shaft of the electric motor passes. The disc and the shaft are rigidly connected. The spring (1 which carries the wei ht e is positioned on the disc and held by t e clamp 0. d and e together are the centrifugal mass. A lever of the second classf is pivoted at the centre 6 of the disc a; the short arm of this lever is connectedtothe weight 6 by the rod 9 and the long arm of the lever has a small contact plate h which is brought into contact with the contact stud c' fastened on the disc, by a movement of the lever The rod 9 is pivotally connected to weight 6 and lever f by pivots 1 and 2. If the spring (21 is in a state of rest, the contacts h and i are opened by suitable adjustment of the screw 70. If the disc a rotates, the mass e tends to move outwardly in a radial direction and at a certain speed of the motor, overcomes the resisting stress of the spring 03. The mass 6 may be said to be then in a state of equilibrium, its centrifugal force being just equal to the force of the spring d.

Under the influence of the force of gravity, the now freely movable spring 03 carries out the known oscillations which are transferred to the movable contact h by means of the lever g in an amplified degree. The contact between h and 2' is then pulsatorily effected for a certain critical speed, and the field current or the armature current of the electro-motor is wholly or partly led across this contact in the known way.

If the lever f is elastic, it is firmly fixed at its centre of movement to disc (1 and tuned to the critical speed by altering the length of the lever f or by loading the lever b a special additional weight, or finally by uslng both means.

Having disclosed several embodiments of our invention, we are entitled to all modifications thereof that fairly fall within the scope of the following claims:

1. A speed controlling device comprising a rotatable plate, a vibrating member fastened to said rotatable plate adapted to be actuated by centrifugal and gravitational forces, a second member pivoted on said rotatable plate, an electrical contact device on said second member, and means connecting said members for causing said second memher to be moved by the first mentioned memher through a larger angle than the angle through which the first mentioned member moves.

2. A speed controlling device comprising a rotatable plate, an electrical contact device fixedly positioned on said plate, a vibrating member connected to said plate and adapted to move under the action of centrifugal and gravitational forces in an are about a point not the center of rotation of said Lil plate, a second member pivoted to move about the center of rotation of said plate, a contact device on said second arm adapted to cooperate with a first mentioned contact device, and a link connecting said members, the distance between the pivot point of the last mentioned member and its connection point with said link being smaller than the distance between the point about which said first mentioned member swingsand its conne'cting point with said link.

3. A speed controlling device comprising in combination a rotatable member, an electric contact device fixedly attached thereto, a vibrating arm fixed at one end to an off center point of said member, said arm having a mass adapted to be actuated under gravitational and centrifugal forces disposed at the other end thereof, a second arm pivoted at the center of rotation of said member, a contact device at the free end of said second arm for cooperating with the first mentioned contact, and a link having one end connected to said first mentioned arm in proximity to said mass and having its other end connected to said second mentioned arm at a point intermediate the pivot and the contact device so that the distance between said point and said pivot is relatively small as compared with the distance between the connecting point'of said link to said first mentioned arm and its fixed end.

4. A speed regulating device comprising a rotatable member, a centrifugally affected mass elastically attached thereto, and adapted to be affected by gravitation in such way that the natural vibratory period thereof corresponds to the regulative speed, electric con tacts mounted on said member and adapted- ,member adapted to be mounted upon a motor shaft, a vibratory centrifugally affected mass attached thereto, and electric contacts adapted to be actuated thereby, a motion amplifying linkage connected between said mass and said contacts.

7. In a device for controlling the speed of an electricmotor, a rotatable member mo'..nted on the shaft thereof, an elastically mounted mass attached thereto andadapted to move with respect thereto under gravitational and centrifugal forces, electric contacts attached to said member and adapted to be actuated by said mass and arranged so as to be substantially free from centrifugal effects, and a movement multiplying linkage connected between said mass and said contacts whereby the movement of said contacts is greater than the movement of said mass.

8. A speed controlling device comprising a rotatable member, an elastically mounted mass attached thereto and adapted to move with respect to the center of rotation of said member under gravitational and centrifugal forces, a fixed electric contact attached to said member and a second cooperating contact, said second contact being disposed on an arm ivoted at the center of rotation of said memer and a link having one end connected to said arm at a point intermediate the pivot and the second contact and connected at the other end to said elasticall mounted mass, whereby the movement of t e contact end of said arm is greater than the movement of said mass.

9. A speed controlling device comprising a rotatable member, an elastic strip fixed at one end to an off-center point of said member and having a mass disposed at the, other end thereof, whereby said mass is adapted to move undergravitational and centrifugal forces, a fixedelectric contact attached to said member and a cooperating movable contact disposed at one end of an arm said arm being pivoted at the other end at t e center of retation of said rotatable member and a link connected at one end to said elastic strip in proximity to said mass and connected at the other end to a point on said arm intermediate thepivot and the movable contact.

DR. OTTO BGHM.

DR. WILHELM MOSER. 

